Method of non-woven fabric for base cloth of carpet

ABSTRACT

The present invention relates to a method of preparing non-woven fabric for base cloth of carpet, which has an improved fixability of BCF yarn inserted on a base cloth in a tufting process by crimp processing a web with a stretched polyester filament and needle punching the web. The residual stress of the stretched polyester filament is eliminated and the formability of the non-woven fabric for base cloth of carpet is improved, and the fixability of the BCF yarn in the carpet can be improved by interlacing of polyester filament.

TECHNICAL FIELD

The present invention relates to a method of preparing non-woven fabricfor base cloth of carpet, which has an improved fixability of BCF(bulked continuous filament) yarn inserted on a base cloth in a tuftingprocess for manufacturing a carpet.

BACKGROUND ART

Carpets are used not only for decoration in hotels, offices, homes,cars, but also for providing amenity and sound insulation.

The carpet fabric is manufactured through a process including a tuftingstep of introducing BCF yarn to a non-woven fabric and a back coatingstep of coating a solution such as PVC, PE, EVA or SBR, etc. the backside of the tufted non-woven fabric and curing. The carpet fabric is cutinto squares (for example, 50 cm×50 cm) to be used as tile carpets inhotels, offices, homes, etc., and molded in the form of a car floor tobe used as a car floor mat.

The function of the base cloth of carpet is to fix the BCF yarn.

In the tufting process, the base cloth is punctured by a needle to haveopen hole of at least 160,000 holes/m². The base cloth must maintain thearrangement of the BCF yarns in even though such physical damage andhave no deformation of the shape in the post-process at the hightemperature environment.

Recent trends in the tufting process are densification, diversificationof pattern and the use of low denier BCF. For example, there is atendency to increase the tufting density by using microfibers of BCFyarns, to make at least three BCF yarns at multilevel conditions, and toincrease the movement of needles by using BCF yarns of various colors.Tufting becomes more difficult. Accordingly, the fixability of the BCFyarn in the non-woven fabric for base cloth has to be improved byincreasing the coefficient of friction between the non-woven fabric andthe BCF yarn so as to prevent the damage to the base cloth.

Meanwhile, conventional non-woven fabric for base cloth of carpet isproduced by stretching and a thermal or chemical bonding of thefilaments having potential stress. After that the residual stress of thefilament is removed by heating in the post-processing for themanufacture of carpet, thereby exhibiting a high shrinkage ratio. Due tothis, there is a problem that the shape of the final carpet product isdeformed.

DISCLOSURE Technical Problem

In order to solve the above problems, the present invention provides amethod of preparing non-woven fabric for base cloth of carpet, which hasan increased fixability of BCF by improving a method of preparingnon-woven fabric for base cloth of carpet.

Technical Solution

In order to solve the above-mentioned problems, the present inventionprovides a method of preparing non-woven fabric for base cloth of carpetcomprising: preparing stretched polyester filament fiber having circularcross section; forming a web by integrating the filament fiber in a webform, crimp processing and calendering it; and needle punching the web.

Advantageous Effects

According to the present invention, the web with the stretched polyesterfilament is crimp processed and needle punched. By this the residualstress of the stretched polyester filament is eliminated and theformability is improved, and the fixability of the BCF yarn can beimproved by interlacing polyester filament.

BEST MODE

The present invention relates to a method of preparing non-woven fabricfor base cloth of carpet comprising: preparing stretched filament toform a web, crimp processing and calendering and needle punching theweb.

The present invention may use filament fibers having a circular crosssection and a low fineness such as 4 to 7 deniers, which is produced bymelting a polyester having a melting point of at least 250° C.,discharging it through a spinneret to form a filament and stretching thefilament to a spinning speed of 4,500 to 5,000 m/min using an airstretching device of high pressure.

In the present invention, when the fineness is less than 4 deniers, thedamage of fibers occurs during tufting and the fixability of the BCFyarn may be deteriorated, and when the fineness is more than 7 deniers,the coefficient of friction may be lowered and it can be difficult toimprove the pullout strength.

The flexibility of the filament may be given by piling up the filamentfibers on the conveyor in the form of a web and heating and crimpprocessing them.

The crimp processing is a processing method of heat treatment ofsynthetic fiber filament to form a thin curvature, and the yarn becomescurl and flexible accordingly.

In the present invention, the stretched filaments may be piled up on aconveyor net and at the same time, be treated at 100 to 150° C. for 30to 60 seconds.

Since the residual stress of the stretched filament is removed byheating in the crimping process, the shrinkage rate of the filament islowered and the shape stability can be improved. Further, since thefilament constituting the non-woven fabric is provided with a crimp andhas a high coefficient of friction, and finally the fixability of theBCF yarn can be improved.

The number of crimps of the polyester filament fiber in the crimpingprocess is preferably 20 to 40/inch. At this time, if the number ofcrimps is less than 20/inch, the contact points between the filamentsare decreased and the strength and elongation of the non-woven fabricafter calendering or needle punching are lowered, and the force to fixthe BCF yarn after tufting is weakened. When the number of crimpsexceeds 40/inch, the contact points become too large and the filamentsmay be damaged due to excessive adhesion between the filaments duringneedle punching and the coefficient of friction of the non-woven fabricis too high, thus BCF yarn with a low fineness may be damaged whentufting.

Thereafter, a non-woven fabric in which interlacing is formed betweenthe filaments can be produced by passing crimp processed web through acalendering roll to adjust its thickness and needle punching it.

According to the calendering of the present invention, it has athickness of 0.35-0.50 mm by applying a predetermined temperature(130-150° C.) and pressure to reduce the thickness of the non-wovenfabric. Accordingly, the density increases and the amount of filamentfor interlacing increases.

Preferably, the needle punch is performed in two steps. The first step(pre-punching) is performed in the condition of 300 to 400 stroke rpm(the speed at which the non-woven fabric is bonded by the needle duringpassing through the conveyor net) to form a web shape by interlacing aportion of the filament. In the second step (main punching), thefilaments are interlaced entirely with a condition of 600 to 800 strokerpm to produce a non-woven fabric for base cloth of carpet.

In the non-woven fabric for base cloth of carpet produced as describedabove, the potential stress of the amorphous region oriented in thestretched filament is eliminated by the crimp processing. In thesubsequent process, the shrinkage rate is reduced due to heat and thecurvature is formed to increase the interlacing point of the filament.Thus, increased tensile strength and tear tension of the non-wovenfabric may exhibit in the needle punching process.

Hereinafter, the present invention will be described in more detail withreference to the following Examples and Comparative Examples.

It should be noted, however, these embodiments of the present inventionhave been described for illustrative purposes, and therefore, thepresent invention is not limited thereto, and it will be apparent tothose skilled in the art that modifications and variations could be madewithout departing from the scope and the spirit of the present inventionas defined by the appended claims.

Example 1

Polyethylene terephthalate (PET) for fibers having a melting point of260° C. was melted in an extruder at 288° C. and discharged throughcapillaries of the spinneret. The discharged PET was solidified by usinga cooling wind, and then stretched using a stretching device and spun ata spinning speed of 5,000 m/min. Thus, filament fiber having a circularcross section with a fineness of 6 denier was produced.

The crimp processing was performed such that the filament fiber waspiled up on a conveyor net in form of a web and simultaneously thestacked filament was heated at 130° C. for 60 seconds to form a crimpnumber as shown in the following Table 1.

Thereafter, the calendering was carried out by passing through a heatedcalendering roll to have smoothness and appropriate thickness to thenon-woven fabric.

Then, the needle punching of the first and second steps were performedin the conditions shown in Table 1 below to produce a non-woven fabricfor base cloth of carpet having an interlaced filament and a weight perunit area of 120 g/m².

Examples 2 to 4

A non-woven fabric for base cloth of carpet was prepared by the samemethod as the Example 1, except that crimp processing and needlepunching were carried out in the conditions shown in Table 1 in theExample 1.

Comparative Examples 1 to 4

A non-woven fabric for base cloth of carpet was prepared by the samemethod as the Example 1, except that crimp processing and needlepunching were carried out in the conditions shown in Table 1 in theExample 1.

TABLE 1 First step Second step needle punching needle punching conditioncondition Example Crimp number (stroke rpm) (stroke rpm) Example 1 20350 700 Example 2 30 350 700 Example 3 40 350 700 Example 4 30 350 800Comparative 15 350 700 Example 1 Comparative 30 350 500 Example 2Comparative 50 350 700 Example 3 Comparative 30 350 900 Example 4

The Examples and Comparative Examples were evaluated by the followingevaluation methods and the results thereof are shown in the followingTable 2.

<Evaluation Method>

1. Tensile Strength (Kgf/5 cm) and Elongation (%)

KS K 0521 method was used. A specimen having a size of length×width=5cm×5 cm was measured by a measuring instrument of Instron with fixing bya jig having upper/lower 5 cm×5 cm at a tensile speed of 200 mm/min.

2. Formability

After applying PVC solution on the back of the non-woven fabric anddrying it, a lattice pattern with gap of 2 cm is drawn on the specimenhaving a size of length×width=50 cm×50 cm. Thereafter, the non-wovenfabric is preheated at 180° C. for 3 minutes in a preheating plate andthe molding is performed using a square mold having a size of 20 cm×20cm with the engraved lower plate and the embossed upper plate. Aftermolding, the number of lattice patterns at the torn portion in thenon-woven fabric was counted to obtain the width of the torn portion.

Number of cells in torn area=2 cells=2×2=4  Ex)

3. Pullout Strength (gf)

Loft type tufting is performed at a speed of 800 rpm under the conditionof 10 needles per inch in the width direction and 13 needles per inch inthe length direction when tufting. After tufting, one adjacent loop tothe loop to be measured is cut off and a loop with 10 loops apart on theopposite side is cut off. An average of 10 intensity peaks appearingwhen the loops to be measured are pulled in a direction perpendicular tothat of the non-woven fabric using an Instron is calculated. The numberof specimens is three.

TABLE 2 Tensile Tensile strength elongation Pullout Overall (MD/CD,(MD/CD, formability strength eval- kgf/5 cm) %) (cm × cm) (gf) uationExample 1 14.1/15.7 34.2/35.9 0 2.1 ◯ Example 2 15.9/16.3 31.4/34.3 02.6 ⊚ Example 3 18.8/20.7 28.3/29.2 0 2.8 ⊚ Example 4 17.3/18.829.4/30.1 0 2.7 ⊚ Comparative 10.1/12.5 40.6/37.4 7 Tufting X Example 1impossible Comparative 14.3/15.1 30.3/34.7 3 2.3 Δ Example 2 Comparative23.8/24.7 38.9/37.6 4 2.4 Δ Example 3 Comparative 10.8/11.7 39.8/38.1 15Tufting X Example 4 impossible

From the results of the Table 2, when the number of crimps of thefilaments constituting the non-woven fabric was small (ComparativeExample 1), tufting was impossible. It is considered because the numberof contact points was small and the friction coefficient was improvedwith minimal compared with Example 1. When the number of crimps of thefilaments is large (Comparative Example 2), the mechanical strength isimproved, but the non-woven fabric becomes stiff and the formability isdeclined.

When the needle punching was excessive (Comparative Example 4), tuftingwas impossible, which is confirmed by the damage of the filament. Whenthe needle punching is performed in small degree (Comparative Example2), the mechanical strength is not improved and the formability islowered.

INDUSTRIAL APPLICABILITY

From the above, it can be seen that the non-woven fabric according tothe present invention is improved in formability and pullout strength inthe process of preparing a carpet, thereby contributing the improvementof productivity and quality of the carpet.

1. A method of preparing non-woven fabric for base cloth of carpetcomprising: preparing stretched polyester filament fiber having circularcross section; forming a web by integrating the filament fiber in a webform, crimp processing and calendering it; and needle punching the web.2. The method of preparing non-woven fabric for base cloth of carpet ofclaim 1, wherein the crimping processing is performed such that thestretched filament fiber is piled up on a conveyor net for forming theweb and at same time, the stretched filament is treated at 100 to 150°C. for 30 to 60 seconds to form number of crimps of 20 to 40 per inch.3. The method of preparing non-woven fabric for base cloth of carpet ofclaim 1, wherein the needle punching is performed in a first step and asecond step and in a condition of 300 to 400 stroke rpm in the firststep and 600 to 800 stroke rpm in the second step.
 4. A non-woven fabricfor base cloth of carpet prepared by the method of claim 1, whichcomprises a polyester filament fiber having a monofilament fineness of 4to 7 denier, and has a pullout strength of 2.0 to 3.0 gf (strength topull loop after loop type tufting) in the non-woven fabric.
 5. Anon-woven fabric for base cloth of carpet prepared by the method ofclaim 2, which comprises a polyester filament fiber having amonofilament fineness of 4 to 7 denier, and has a pullout strength of2.0 to 3.0 gf (strength to pull loop after loop type tufting) in thenon-woven fabric.
 6. A non-woven fabric for base cloth of carpetprepared by the method of claim 3, which comprises a polyester filamentfiber having a monofilament fineness of 4 to 7 denier, and has a pulloutstrength of 2.0 to 3.0 gf (strength to pull loop after loop typetufting) in the non-woven fabric.